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Friday, 5 July, 2002, 11:18 GMT 12:18 UK
Winds hamper Martian landing
View of Mars through the eyes of Beagle 2 (University of Wales)
View of Mars through the eyes of Beagle 2

Bad weather on Mars could force a detour for the British-led effort to land on the planet.

Scientists want to change the point of touchdown of the Beagle 2 craft to reduce the risk of a crash landing.

Weather on Mars
Average surface temperature -63C
Thin, inhospitable atmosphere
Dust storms can swirl across the planet for months
Dust devils reaching several km in height race across the surface
Evidence has emerged of strong gusts of wind on the Martian surface in the landing zone, a giant basin north of the planet's equator.

There is concern that the lander could tumble over the surface of the Red Planet then crash.

Beagle 2 is designed to withstand such damage, but nobody really knows what it will encounter as it rolls across the rocky surface.

The planned landing site is on Isidis planitia, a large flat region on the boundary between the ancient highlands and northern plains of Mars.

The target zone is 500 kilometres long - about the distance between London and Edinburgh - and 100 km wide. The aim is to land right in the middle.

'High wind'

Dr John Bridges of the Natural History Museum, London, is part of the landing site selection team for Beagle 2.

He told BBC News Online: "There may be a zone of high wind in the southern part of Isidis.

"We are now thinking about this, and wondering whether to tweak our landing site by moving it a bit north and a bit east."

The biggest risk of strong winds is to the south of the basin, according to evidence from Oxford University's climatology research group.

Mars Odyssey (Nasa/AP)
Nasa's Mars Odyssey is looking for water
Just like on Earth, it is possible to predict the weather on Mars using computer modelling.

However, data for Mars is scarce. What little there is comes from a Nasa spacecraft, Mars Global Surveyor, currently mapping the planet, and old evidence from the Viking Mars missions of the 1970s and the Pathfinder mission five years ago.

Dr Stephen Lewis of Oxford University's physics department says there appear to be wind gusts up to 720 kilometres per hour (447 miles per hour) in the upper atmosphere of Mars.

These drop to around 36 km/h (22 mph) close to the Martian surface, a concern for any craft attempting to land.

Dust storms

"I would expect a wind blowing towards the south and the east of around 8-10 metres per second at the sort of [landing] heights they are worrying about," Dr Lewis told BBC News Online.

"If a large dust storm were going on anywhere on the planet, or a local dust storm, then the winds could be much higher."


Small landers like Beagle should be rather less affected than great big heavy one like the Nasa ones

Dr John Bridges, Natural History Museum
Beagle 2 is hitching a ride on the European Space Agency's Mars Express spacecraft.

Agustin Chicarro, project scientist for the Mars Express mission, says major dust storms, which can smother the entire planet for months, are not predicted when Beagle lands.

He told BBC News Online: "Beagle will land at the very beginning of the summer spring on Mars and it's a time when global dust storms are not expected.

"Typically, they will start to grow in the southern hemisphere in the southern summer and then if they grow into a global phenomena, they will travel to the north.

"If that happens during the year - which is not certain at all - by that time, Beagle will probably not be alive anymore, because its planned lifetime will be about six months."

Space race

Dr Bridges says they will come to a decision in the next few weeks on whether to re-jig the landing site.

Any detour would need approval from the European Space Agency.

But Dr Chicarro believes small adjustments "by a few degrees in latitude" would not pose a problem for the spacecraft.

Ironically, perhaps, the mission itself will reveal more about weather on Mars.

The spacecraft - due to arrive at Mars in December 2003 - carries instruments to watch for clouds, fog, dust devils, and storms, which whip across the Martian surface.

It will also look for clues to explain past and present climate change on the Red Planet.

Winds present across much of the equatorial latitudes of Mars may also be a problem for Nasa which is planning to send landers to the planet about the same time.

"No lander wants too high a wind as it comes in, certainly in the last few hundred metres of elevation, because it might pick up too much velocity," says Dr Bridges.

"Small landers like Beagle should be rather less affected than great big heavy ones, like the Nasa ones," he says. "So, it's not such an intense problem for Beagle."

See also:

27 May 02 | Science/Nature
20 Dec 00 | Science/Nature
13 Sep 00 | Festival of science
05 Jul 02 | Science/Nature
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